"I'm doing five events this weekend right here in Iowa. We're all over New Hampshire, South Carolina, Nevada, California. But he's too important," Sanders said, referring to reports that Bloomberg would not aggressively compete in the first four voting states. "You see, when you're worth $50 billion, I guess you don't have to have town meetings, you don't have to talk to ordinary people. What you do is you take out, I guess a couple of billion dollars, and you buy the state of California."

The comments from Sanders came just a day after Bloomberg, a billionaire businessman, filed as a candidate for the Alabama Democratic presidential primary, a first step in a potential 2020 White House bid.

While Bloomberg has not made a final decision on whether to run, the move has led to mounting questions about how his candidacy could impact the crowded 2020 Democratic primary field.

Sanders has made combatting inequality and reigning in financial excess among massive corporations a staple of his campaign for president. He often rails against billionaires and what he views as a system that doesn't tax them enough.

Warren, who has echoed many of those talking points, has also taken issue with a possible Bloomberg candidacy.

“The wealthy and well connected are scared,” Warren’s campaign said in an email to supporters as news broke that Bloomberg was considering a run. “They're scared that under a Warren presidency, they would no longer have a government that caters to their every need. So they're doing whatever they can to try to stop Elizabeth and our movement from winning in 2020 and bringing big, structural change in 2021.”

Bloomberg announced in March that he would not seek the 2020 Democratic presidential nomination. At the time, he cautioned the party against choosing a candidate that would “drag the party to an extreme that would diminish our chances in the general election.”